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This paired-watershed study aims to isolate natural variations in stream water quality from those potentially associated with forest fertilization, and in doing so, assess Florida best management practices (BMPs) for fertilization. Using novel, in situ monitoring, high resolution (sub-hourly to sub-daily) streamflow and water quality data are being collected for baseline and post-fertilization conditions in two first-order, coastal blackwater streams draining approximately 6,000-acre watersheds in North Florida. This high frequency data collection includes: nitrate (NO3-), soluble reactive phosphorus (SRP), colored dissolved organic matter (CDOM), dissolved oxygen (DO), turbidity, stage, discharge, and pH. Following a year-long sampling period, results for baseline conditions illustrate dissimilarities among solute behaviors within each watershed based on loading and concentration, as well as event-driven dynamics compared to seasonal averages. Following baseline measurements, maximum allowable levels of elemental N and P were applied using diammonium phosphate (DAP) and urea fertilizers to one watershed in accordance with commercial pine management using aerial techniques. The post-fertilization response is being evaluated in the context of concentration-discharge (C-Q) relationships of solutes, as well as residence time within the watersheds using tracer isotopes. In general, assessing anthropogenic impacts requires a clear understanding of natural variations occurring over both long and short temporal scales. Available in situ sensors and high resolution data provide this information across a set of parameters and temporal scales, and give evidence of possible timescales of responses to fertilization, which would otherwise not be possible with conventional monitoring practices. |